When it comes to making electrical connections between conducting elements using aluminothermic welding, where aluminothermic charges are used which, due to the ignition, cause the exothermic reaction which produces the necessary heat to create the welding, the traditional way to start said reaction comprises the use of what it is known as ignition powder and a spark-generating pistol.
The ignition power is a mixture of components that are similar to those making up the aluminothermic charge, but with a much smaller grain size. For this reason, the ignition powder is capable of being ignited with a much lower energy input than that needed to ignite the aluminothermic charge. In fact, the sparks generated by the pistol are enough to ignite the ignition powder. Once this has occurred, the energy that was freed during the reaction of the ignition power is enough to initiate the reaction of the aluminothermic charge itself.
In order to carry out such welding, a mold, in which the components to be joined are arranged, is used, in addition, said mold comprises a chute-crucible where the aluminothermic charge is placed. Subsequently, most of the ignition powder is poured over said aluminothermic charge to ensure that the aluminothermic reaction will be initiated simultaneously in multiple stages of the aluminothermic charge, a condition necessary for the correct propagation of that reaction.
A small amount of the ignition powder that is not poured over the aluminothermic charge is saved to be poured in an area with an easy access for the ignition pistol. Commonly, and if the mold incorporates a lid with an opening (being either a lid with a simple opening, which communicates directly with the interior of the crucible, which may not, therefore, prevent projections towards the exterior, or a lid with an adapted opening to retain the projections), said small amount of ignition powder is poured on the upper part of the mold and on the side of an opening provided on the lid. This way, it is easy to bring the pistol near that small amount of ignition powder and cause the ignition of said small amount of powder. Some of the sparks generated during the reaction of the small amount of ignition powder go through the lid opening towards the interior of the chute-crucible, where most of the ignition powder was previously poured, so that the reaction of said ignition powder will be caused which will, in turn, cause the reaction of the aluminothermic charge.
This process of chain reactions takes places almost instantaneously, in a very abrupt manner, and for this reason it is necessary that the welding operator quickly removes the hand with which the pistol is actuated. Otherwise, the particle projections that are produced during the reaction of the aluminothermic charge could cause him burns.
One solution to this disadvantage is shown in national patent application P200803232, made by KLK Electro Materiales, S.A., where a special lid is described which fulfills the function of evacuating the reaction's gasses, but retaining all of the solid particles inside the mold.
In P200803232 it is shown that one of the parts of the special lid may be used for, besides depositing the ignition powder, placing over it either the ignition pistol or the remote ignition capsule. That is, the special lid is apt to be used in a process of remote ignition with a capsule. Besides achieving increased safety, a remote ignition process is desirable when, for example, it is necessary to weld in areas with difficult access.
There are solutions currently known which contemplate the remote ignition of charges. However, they refer to very bulky devices and, therefore, difficult to transport and handle, as well as requiring high energy consumption to produce the ignition.